OperatingSystemsChapter 9, part 1File Systems - Programmer Perspective
Operating Systems Chapter 9, part 1 File Systems – Programmer Perspective
Story so far...UserSpaceProcessesFile systemImplementationOperatingSystemKernelFAT32,EXT2/3FileSystemOperationsKV,DistributedFSGraphSystem...SCSalid SisDevices25669512G8
Story so far. 2 File System Operations Operating System Kernel User Space Devices Processes File system Implementation FAT32, EXT2/3 KV, Distributed FS, Graph System
Outline· File system introduction. What are stored on a storage device?- File-Directory-Interfaces/Operations3
Outline • File system introduction • What are stored on a storage device? – File – Directory – Interfaces/Operations 3
File system introduction4
4 File system introduction
IntroductionProcessAUserspaceFSOperationsOperatingSystemKernelDevicesTo understand what a file system (Fs) is, we followtwo different, but related directions:Layout&Operations5
Introduction 5 FS Operations Process A Operating System Kernel User space Devices ⚫ To understand what a file system (FS) is, we follow two different, but related directions: - Layout & Operations
IntroductionProcessAUserspaceFSOperationsOperatingSystemKernelThe layout.DevicesEvery Fs has an unique layout on thestorage device. The layout defines:- What are the things stored in the device.-Where the stored things are.6
Introduction 6 FS Operations Process A Operating System Kernel User space The layout. Every FS has an unique layout on the storage device. The layout defines: - What are the things stored in the device. - Where the stored things are. Devices
IntroductionProcessAUserspaceFSOperationsOperatingSystemKernelThe layout.DevicesTheset of FSoperationsdefineshowtheOSshouldworkwiththeFSlayout.Inotherwords,OsknowstheFslayoutand workswiththatlayout
Introduction 7 FS Operations Process A Operating System Kernel User space The layout. Devices The set of FS operations defines how the OS should work with the FS layout. In other words, OS knows the FS layout and works with that layout
IntroductionProcessAUserspaceFSOperationsOperatingSystemKernelThe layout.DevicesThe process uses system calls, whichthen invoke the Fs operations, to accessthe storage device.8
Introduction 8 FS Operations Process A Operating System Kernel User space The layout. Devices The process uses system calls, which then invoke the FS operations, to access the storage device
Introductionfopen()fread()fwrite()fclose()LibraryCallsProcessclose()open()read()write()SystemCallsKernelExt4-FAT32-NTFS-ISO9660-KernelspecificspecificspecificspecificFunctionsfunctionsfunctionsfunctionsfunctionsDevices9
9 Introduction fopen() fread() fwrite() fclose() Library Calls NTFSspecific functions Ext4- specific functions FAT32- specific functions ISO9660- specific functions Kernel Functions open() read() write() close() System Calls Process Kernel Devices
Summary·Ask yourself:-OS=FS?- Correct answer: OS ± FS-An OS supports a FS: An OS can support more than one FS: AFS can be read by more than one OS10
Summary 10 • Ask yourself: – OS = FS? – Correct answer: OS FS – An OS supports a FS • An OS can support more than one FS. • A FS can be read by more than one OS